HIV-1 (human immunodeficiency virus-1) infection remains a major medical problem, with tens of millions of people still infected worldwide at the end of 2011. The number of cases of HIV and AIDS (Acquired Immuno Deficiency Syndrome) has risen rapidly. In 2005, for example, approximately 5 million new infections were reported and 3.1 million people died from AIDS. Despite continued advances in HIV treatment options, the development of new antiretroviral drugs and regimens continues to represent an important area of unmet medical need due to long-term tolerability concerns and the emergence of viral strains resistant to current therapies. To date, the approved therapies to treat HIV infection fall into 4 general classes: (1) reverse-transcriptase inhibitors, (2) protease inhibitors, (3) integrase inhibitors and (4) entry inhibitors. Examples of available drugs for the treatment of HIV include nucleoside reverse transcriptase (RT) inhibitors or approved single pill combinations: zidovudine (or AZT or RETROVIR®), didanosine (or VIDEX®), stavudine (or ZERIT®), lamivudine (or 3TC or EPIVIR®), zalcitabine (or DDC or HIVID®), abacavir succinate (or ZIAGEN®), Tenofovir disoproxil fumarate salt (or VIREAD®), emtricitabine (or FTC or EMTRIVA®), COMBIVIR® (contains -3TC plus AZT), TRIZIVIR® (contains abacavir, lamivudine, and zidovudine), EPZICOM® (contains abacavir and lamivudine), TRUVADA® (contains VIREAD® and EMTRIVA®); non-nucleoside reverse transcriptase inhibitors: nevirapine (or VIRAMUNE®), delavirdine (or RESCRIPTOR®) and efavirenz (or SUSTIVA®), ATRIPLA® (TRUVADA®+SUSTIVA®), and etravirine, and peptidomimetic protease inhibitors or approved formulations: saquinavir, indinavir, ritonavir, nelfinavir, amprenavir, lopinavir, KALETRA®(lopinavir and Ritonavir), darunavir, atazanavir (REYATAV), and tipranavir (APTIVUS®), and integrase inhibitors such as raltegravir (ISENTRESS®), and entry inhibitors such as enfuvirtide (T-20) (FUZEON®) and maraviroc (SELZENTRY®).
The identification of potent, orally active antiretrovirals with a unique mechanism of action led to HIV attachment inhibitors a novel subclass of antiviral compounds that bind to the HIV surface glycoprotein gp120, and interfere with the interaction between the surface protein gp120 and the host cell receptor CD4. Thus, they prevent HIV from attaching to the human CD4 T-cell, and block HIV replication in the first stage of the HIV life cycle. The properties of HIV attachment inhibitors have been improved in an effort to obtain compounds with maximized utility and efficacy as antiviral agents.
One HIV attachment inhibitor compound, in particular, has now shown considerable prowess against HIV. This compound is identified as 1-(4-benzoyl-piperazin-1-yl)-2-[4-methoxy-7-(3-methyl-[1,2,4]triazol-1-yl)-1H-pyrralo [2,3-c]pyridine-3-yl]-ethane-1,2-dione, and is set forth and described in U.S. Pat. No. 7,354,924, which is incorporated herein in its entirety: The compound is represented by the formula below:

The above compound is the parent compound of the prodrug known as 1-benzoyl-4-[2-[4-methoxy-7-(3 -methyl-1H-1,2,4-triazol-1-yl)-1-[(phosphonooxy)methyl]-1H-pyrrolo[2,3-c]pyridin-3-yl]-1,2-dioxoethyl]-piperazine. It is set forth and described in U.S. Pat. No. 7,745,625, which is incorporated by reference herein it its entirety. The compound is represented by the formula below:

Various methods for making this prodrug compound have been set forth, including those detailed in the '625 reference. In particular, the '625 reference includes various methods for acylation, alkylation and phosphorylation. Another patent reference, U.S. Pat. No. 8,436,168 entitled “Methods of Making HIV Attachment Inhibitor Prodrug Compound and Intermediates”, also details various procedures for making the piperazine prodrug compound. These include a multi-step process which uses the compound
as a starting material, which is subsequently brominated, and then nitrated. Further on, a triazolyl moiety is added to the compound before further attaching the piperazine moiety separated by dual carbonyl groups. Yet another patent reference, U.S. Pat. No. 8,889,869 filed Feb. 6, 2013, entitled “Methods for the Preparation of HIV Attachment Inhibitor Piperazine Prodrug Compound”, also details procedures for making the compound. These include a multi-step process which uses the compound N-sulfonylated pyrrole as a starting material, which is subsequently subjected to a Friedel-Crafts acylation reaction, Pictet-Spengler cyclization, two oxidation reactions followed by bromination, deprotection and a second Friedel-Crafts acylation. Further on, the piperazine moiety is incorporated by amidation of the dual carbonyl groups followed by the copper catalyzed reaction to install the triazolyl moiety.
What is now needed in the art are new methods of making the halogenated azaindole compounds so as to prepare piperazine prodrug compounds which are useful against HIV. The methods should be economical and also be able to produce the halogenated azaindole in high yield and selectivity.